A common problem on 1999-2007 trucks is the failure of the blower motor resistor and connector. Over time, the resistor and wiring can overheat, melting the connector and wires. This will cause the fan to work on low or high speed only, run continuously or not at all. Replace both the blower motor resistor and connector to get the blower motor working properly again. Will not work on models with automatic climate control.
There are two different resistor designs for 2003-2007 models. Before ordering, determine which resistor you need by the production option codes listed at right and the number of resistor mounting holes shown in the photos above.